Dynamo-electric machine.



H. A. BALGOME.

DYNAMO ELBGTRIO MACHINE.

APPLIUATIOH FILED JULY 1,1901.

91 1,364, Patented Feb. 2, 1909.

2 SHEETS-BREE! 2.

Z m -3 mm WM W this metal for small or medium size motors,

'of Massachusetts, have invented an Im-i UNITED STATES PATENT OFFICE.

HERBERT A. HALO-ONE, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO HOLTZER-CABO'I ELECTRIC COMPANY, A CORPORATION OF MASSACHUSETTS.

DYNAMO-ELECTRIC MACHINE.

Specification of Letters Patent.

Patented Feb. 2, 1909.

Application filed July 1, 1907. Serial No. 881,622.

To all whom it may concern: I Be it known that I, HERBERT A. BAL-, COME, a citizen of the U 'ted States, residing l in Boston, in the county 0 Suffolk and State provemen-t in Dynamo-Electric Machines, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings replresenting like parts. .he present invention relates to an electric motor, the purpose of the invention being to produce a motor which will deliver the greatest amount of energy or power, with the least possible expenditure of material and labor in its construction.

In order to accomplish this end, it is neces' sary that all the material used should be the most eificient for the particular duties which it is designed to perform. Soft or low car-, bon stee is commonly used for the field magnets of such motors, but on account of the long dela necessary to obtain this, the great cost 0 machining, and the general unsatisfactory results attending the use of it is desirable to use some other metal. (last iron, often used, does 'not fill the requirements on account of the low magnetic cilicienoy per unit of weight, so that the only other metal which can be used is wrought 11011.

It is the usual practice to use wrought iron for the core of the armature, this bcin laminated in the form of sheets assemble together until the required volume of iron is obtained. The use of wrought iron for the field, however, if made in the form of a forgmg is very expensive, so that in order to reduce the cost of construction, it is desirable to emplo some practicable method of building the old of iron sheets as laminae which may be stamped out to she e in a press and then assembled together. t is a fact, moreover, that within certain limits the output and efficiency of an electric motor armature depends on the amount of copper which there is in its construction, that 1s, the percentage of copper to iron, the output in creasing with t e increase in percentage of copper. In order that the percentage of copper may be great, it is necessary that the slots or channels in the core for the reception of this copper should be as large as possible,

to increase the depth of the slots more than is necessary, it is desirable to make the slots as wide as possible. Armatures having wide slots, however, cannot be operated in a magnetic field having plain polar projections Without vicious sparking, hcating etd, and it becomes necessary that some special formation be resorted to in order to give such magnetic flux distribution as shall nullify the effects usually produced by wide slots.

To make such a polar formation an inlegral art of the field stamping is impracticab e, as it is impossible to get the field or exciting coils on the polar projections over such formation without increasing the size of the motor as a whole. It becomes necessary, therefore, to utilize a detachable polar formation or shoe which may be readily attached in close magnetic. proximity to the stamped polc extremities after the iield exciting coils are in position, and the present invention is embodied in a construction which provides for the desired polar formation, at the same time reserving all the advantages above described, the construction also having other 8 advantages which will be hereinafter pointed out.

Figure 1 is a side elevation of the field core of a four-pole motor completely assembled: Fig. 2 is a vertical section on line :0 of Fig. l, showing also a portion of the motor frame: and Fig. 3 is a perspective view of one of the rings which forms the polar extensions.

The particular construction herein chosen for illustration is the same as that shown and described in an a plication filed by me July 1, 1907, Serial 0. 381,621, and, for convenience, the main part of the motor frame, together with the armature and armature support, are omitted from the drawings, since those parts do not enter into the present invention, and do not need to. be shown for the re or understanding thereof.

T 1e eld core is made up of the lamina: a cut to form the polar extremities a and adapted to be clamped together between the side members A of the motor frame, as indicated in Fig. 2. These side members constitute the main frame of the motor which carries the field, the armature bearings, and 10-? other parts, and the members are held to other with the lamina, which constitute the old core between them by cross members but as it is undesirable for practical reasons 55 lar extensions firmly in place, thereby re- A which are shown as held in place by masses 1' of Babbitt metal A The polar extremities i a receive the coils b in the usual way, the i construction thus far described not diil'ering i in general arrangement from that of motors heretofore manufactured.

in order to extend the polar extremities beyond the laminae so as to obtain a gradually decreasing and increasing magnetic strength as the chan e is made from one polarity to the other, t 1e motor is provided in i accordance with the present invention with the polar extensions which are formed in j annular members or rings 0 having project- 1 ing portions 0 which project inward towards each other from opposite sides along the I edges of the laminated polar extremities. 'lhese rings are placed in position at opposite sides of the field core, as best shown in Fig. 2, j and are clamped together by'means of transverse bolts (1 which not only hold them firmly i in position, but also clamp the laminated poventing the laminae from setting up vi ra tions. The portions 0 and a form enlarged l and extended polar faces which approach each other, the main body of the ring conj members which aso serve to clamp all the larity to the other.

stituting a magnetic conductor from one pole to the other which, however, is not ob- I jectionable, but rather assists in affording a j wave form of magnetic change from one po- This construction ad a laminated wrought iron field, the laminae ein cut with straight polar rojections over w llCl]. the field coils can 1 he s ipped into place, the necessa extended i polar pieces bein supplied by t e annular mits of building up parts together and to hold the coils in place. lhis admits of the use of an armature having wide slots capable of containing a large percentage of copper so as to produce a very efficient motor, the field construction, however, being such that this type of armature 5 can be employed without sparking when the motor is running under a heavy load.

A further advantage of this construction consists in the fact that motors of different capacity can be produced by sim ly varying the number of laminae in the fiel and armature, using identically the same frame and ring castings.

Claims.

1. In an electric motor, the combination with a laminated field core provided with polar extremities of extended pole pieces formed on annular members at op )osite sides of the field core; and means for clamping said members together with the laminae of the field core between them.

2. In an electric motor, the combination with a laminated field core provided with polar extremities adapted to receive coils;

F of annular members at opposite sides of said field core, said members eing provided with extended portions to form pole faces; and transverse clamping members to hold said annular members in ositionwith the polar extremities clamped between them.

3. In an electric motor, the combination wit-h a laminated field core provided with polar extremities; of annular members at opposite sides of said field core provided with projections extending towards each other at opposite sides of the polar extremities, said members also being rovided with an enlarged portion to aflord polar extensions; and means for clamping said annular members together, and to the field core, substantially as described.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

HERBERT A. BALCOME.

Witnesses:

JAS. J. MALONEY, W. E. CovENEY. 

